Wool shrinkproofing baths containing butadiene copolymers and their utilization



Patented July 11, 1950 UNITED STATES PATENT OFFICE WOOL SHRINKPROOFING BATHS CONTAIN IN G BUTADIENE COPOLYMERS AND THEIR UTILIZATION No Drawing. Application November 28, 1945, Serial No. 831,483

6 Claims. 1

This invention relates to shrinkproofing wool, to copolymerization products useful for that purpose, to emulsions and compositions containing such polymerization products, and to methods of making such products and compositions and of treating wool therewith.

Among materials that have heretofore been suggested for the treatment of wool, may be mentioned methacrylate resins, butadiene copolymers, etc. Those suggestions in the art treat all of these polymeric substances as equivalent for all fibers. But investigation proves that such suggestions are erroneous because while any of the synthetic resins referred to can be applied to wool for example, they'are not equally efllcacious in effecting a shrinkprooi'ing effect. And this is true even of copolymers of butadiene 1.3 derivatives.

Among the objects of the present invention is the production of copolymers particularly valuable in the shrinkproofing of wool but having other utilities as well.

Further objects include the production of baths, emulsions and compositions containing such copolymers.

Further objects include methods of preparing such copolymers and baths, emulsions and compositions containing them.

Still further objects include methods of treating wool for shrinkproofing.

Other objects and advantages of the invention will appear from the more detailed description set forth below, it being understood that this more detailed descriptionds given by way of explanation and illustration only, and not b way of limitation, since various changes therein may be made by those skilled in the art without departing from the scope and spirit of the present invention.

In accordance with the present invention it has been found that copolymers of a butadiene 1.3 and a vinyl ester may be prepared and utilized to give excellent shrinkproofing of wool, the vinyl ester being one which polymerizes to a hard resinous material. Such copolymers may be prepared at high speeds in a relatively short time to produce copolymers possessing valuable properties.

As illustrative of the butadiene 1.3 derivative,

' there may be mentioned particularly, butadiene 1.3, isoprene, dimethyl butadiene, ethyl butadiene, methoxy and ethoxy butadiene, cyanobutadiene, chloroprene, etc., and mixtures thereof.

The vinyl esters of both organic and inorganic acids may be utilized. As organic acid esters there are particularly to be considered the car boxylic acids having a chain of flve or six carbon atoms or less. and the lower fatty acids may be particularly mentioned. Vinyl acetate and vinyl halides particularly vinyl chloride, will be utilized to illustrate the invention.

While various methods of producing the copolymers may be employed, the most desirable method is to carry out the polymerization in an aqueous medium or emulsion in the presence of a polymerization catalyst. The conditions of reaction determine the speed or reaction velocity as well as the characteristics of the products obtained; although the nature of the interpolymerizing constituents has an important effect on those characteristics; and in some instances the proportions of the copolymer ingredients affect the properties insofar as shrinkproofing of wool is concerned. The preferred process includes the steps of heating a mixture of the constituents to be copolymerized with water in the presence of an emulsifying agent and a polymerization catalyst, particularly a peroxide catalyst, in a pressure reactor at a controlled temperature and pH, using agitation to maintain a good emulsion. In this way, emulsions containing the copolymer may be directly obtained and utilized by adjustment and additions as the treating bath for treating the wool to produce shrinkproofing.

By utilizing pressures in excess of atmospheric, the time periods involved may be greatly shortened and the reactions greatly accelerated even at relatively low orders of temperature, to give very satisfactory products. As indicated above, a satisfactory way of carrying out the reaction under pressure is to utilize the stated constituents and reaction mixtures in a closed reactor or reaction vessel, the pressures required being generated under such conditions.

An important consideration in control of the character of product obtained, is the pH at which the reaction is carried out. Desirably, a relatively constant pH should be maintained. The particular pH empoyed depends upon the particular substances being polymerized and also depends upon the mode of polymerization. Desirably therefore, where the polymerization is carried out in an aqueous emulsion, the pH should be accurately adjusted as by neutralization and stabilized as by means of suitable buffering agents at that value best suited for the emulsifying agent employed. Depending upon the individual reactants and the conditions of the reaction, the polymerization may be carried out at a controlled pH between 4 and 11. A pH within the range of 7-11 is preferred.

As buffers there may be mentioned solutions of acetates, borates, phosphates, and the like, or mixtures thereof. The pH employed depends in part on the type of emulsifying agent used. Emulsifying agents should be used which ar stable at the pH concentration employed. With an emulsifying agent which is most eflicient under acid conditions, a pH below 7 is desirable. On the other hand, with emulsifying agents which are most efllcient under basic conditions, a pH above '7 should be employed.

As emulsifying agents, there may be employed I a wide range of materials such as sodium lauryl it is the preferred emulsifier. The proportion of water to be used in the emulsion is subject to wide variation. However, avoiding unnecessarily large quantities of water, enables smaller equipment to be employed.

Reaction temperatures of from 30 to 100 C. may be employed, but more desirably the reaction is carried out between temperatures of 30 to 60 C., particularly under the preferred conditions of operations as illustrated herein.

As indicated, the reaction is desirably carried out in the presence of a polymerization catalyst and any suitable oxygen-giving compound may thus be employed. Preferably the less expensive material such as hydrogen peroxide, ammonium persulfate, benzoyl peroxide, and the like may be utilized.

While additive agents in the emulsion are not necessary, they are often advantageous. Protective colloids may be employed such as gelatin, glue, methyl cellulose, agar agar, alginates, pectates, egg albumin, and the like.

The temperature, amount of catalyst, emulsifying agent, efliciency of agitation, additive agents, and the like, all have an influence on the velocity of the reaction. When the reaction has proceeded as far as desired, there may be added an antioxidant such as phenyl' beta naphthylamine, alkyl aromatic amine, hydroquinone monobenzyl ether, and the like. The presence of antioxidant has an important effect other than merely as an antioxidant in the usual sense, since the presence of such materials in the emulsions and baths used for shrinkprooflng wool, exert an effect whereby the shrinkprooflng is en.- hanced beyond that obtained in its absence. So that antioxidants in these cases have an unexpected and unpredictable effect.

The interpolymerization products are produced in latex-like form when the reactions are carried out in aqueous emulsion as indicated above, and such latex-like products may be utilized as such, for example, in the treatment of textiles, preferably after adjustment as indicated below, or they may be employed in other ways.

As formed, the emulsions contain the copolymer in a condition in which it is unsuitable as synthetic rubber or rubber-like material. If coagulated by any suitable means, the emulsions give crumbly materials which cannot be milled or sheeted as on rubber milling equipment in the way that rubber is manipulated. The copolymer is in the form where extensive cross-linking has occurred as further pointed out below.

To enhance such materials for use for shrinkproofing, they may desirably be given an oxidation treatment, preferably while in aqueous emulsion as obtained from the polymerization step, to convert them into what may be called a prevulcanized condition so that upon deposition of the polymer on, in or about the fibers or textiles, the polymer is in a non-tacky condition and gives a non-tacky deposit. Or the polymer in such emulsions utilized in accordance with the present invention is in a condition in which it is substantially insoluble in organic solvents such as benzene, toluene, xylene, carbon tetrachloride, chloroform, and tetrachlorethane, but, however, may be swollen to some extent with such solvents. The vulcanization has been carried to a point where substantially no soluble polymer remains, but, as stated above, the gel-forming polymer may be swollen to some extent with the stated solvents.

Where such pre-vulcanization by oxidation is employed, the emulsions are prepared by carrying out the polymerization in the presence of polymerizing agents in which emulsions the polymer or copolymer is present in such condition that if deposited on fibers a tacky deposit would be obtained, or the polymer is substantially soluble in common organic solvents at this time, or is incompletely vulcanized, and the emulsion thus prepared is subjected to an oxidative treatment by means of hydrogen peroxide or other substances which liberate oxygen under the conditions of treatment to convert the polymer or copolymer present in such emulsions into a condition where upon deposition on fibers it gives a non-tacky deposit, or gives a deposit which is substantially insoluble in common organic solvents, or is substantially completely vulcanized and in the form of a cross-linked polymer. The first step is carried to a point of substantially complete polymerization, by which is meant little or no monomer is present. The emulsion at this point may be subjected to vacuum or other treatment to remove any volatile hydrocarbons which may be present, before the step of oxidative vulcanization. The term oxidative pre-vulcanization may be used to describe the final condition of the polymer in the emulsion without any implication that an oxygen link is necessarily involved.

Such oxidative pre-vulcanization may be carried out at temperatures for example of 70-100 C., with oxygen yielding substances such as hydrogen peroxide, benzoyl peroxide, ammonium persulfate, acetyl peroxide, butyl hydroperoxide, butyl perbenzoate, etc. for a. period of from 45 minutes to 1% hours. Such oxidative treatment of the emulsion is desirably carried out in the absence of the antioxidants, the latter being added after the oxidation treatment has been carried to the point desired. This addition of antioxidant is desirable so that further oxidative change will not continue after the material has been applied to the textile.

The emulsions produced as set forth above may be used for the treatment of wool either as raw wool, yarn, knit, woven goods or mixed goods, etc. The wool to be treated is entered into the bath containing the copolymer produced as set forth above. Water may be added to such emulsions to produce the desired bath content. The bath should contain the copolymer in an amount to give, under the conditions of treatment, a wool having from 1% to 25% of copolymer based on the weight of the wool. The bath is desirably conditioned by adding to it a suficiently strong electrolyte to allow the deposition of the copolymer on the wool fibers. It has been found that in such a bath no deposition of copolymer occurs under ordinary conditions. However, upon the addition of an electrolyte, exhaustion of the bath will take place with varying rapidity, depending mainly upon temperature and electrolyte concentration. Without any limitation by way of theoretical considerations, it is believed that reversal of the electrical charge on the colloidal particles of the copolymer takes place on addition of the electrolyte enhancing the affinity of the copolymer for the fiber. The proportion of the electrolyte added would be insufficient to account'on a theoretical basis for the salting out of the copolymer particles. Thus the effect must be one of electrical charge rather than precipitation by coagulation. When the electrolyte is added to the treated bath there is no coagulation or precipitation even on heating for relatively long periods of time. It is only in the presence of fibers that deposition occurs. This is additional proof that electrical charge of the particles is involved rather than a salting out effect.

The ratio of the copolymerizing constituents may be varied substantially and a pronounced shrinkproofing effect obtained. With vinyl acetate, the best results were obtained with about 30% based on the weight of the copolymer, although other ratios such as to 40% gave substantial shrinkproofing effects. With vinyl chloride, substantial improvement over the untreated wool was obtained with varying ratios, very marked effects being secured with ratios of 10 to The electrolyte content may vary over substantial limits but sufllcient electrolyte should be present to condition the bath so that the bath, although stable in the presence of the wool fibers, will deposit the polymer in the presence of the conditioning electrolyte. Thus the electrolyte content may vary from about 25% to about 500% based on the weight of the copolymer present. As such electrolyte water soluble salts may be used, desirably such salts which do not precipitate the polymer, neutral salts, specifically salts of strong bases and strong acids, particularly inorganic salts are preferred. The following are exemplary: sodium sulphate, chloride, bromide, iodide, suliite, bisulfate, bisulfite, nitrate, acetate and the like, or the corresponding potassium, lithium, caesium salts, etc. Salts like zinc chloride may also be used were the coagulation does not appear to be too serious since it occurs in small particulate form and the particles may be redispersed by stirring. The term "conditioning electrolyte is used hereinafter to cover such electrolytes which produce the desired deposition of the polymer. It has been found that it is possible to deposit the emulsions of the present invention on wool at a pH of 7 or even slightly higher. However, it is preferred to operate at a pH of '7 or below since under these conditions more rapid dispersal is effected.

Mixed goods including wool-cotton, wool-rayon and so forth can be treated by this method without any deleterious effect. If desired the wool may be subjected to a pretreatment, as for example, chlorination or bromination, before being treated in accordance with the present invention.

As emulsifying agents, I anionic emulsifying agents which are stable at or below pH '7 are preferred. Such emulsifying agents are exemplifled by sodium lauryl sulfonate, sodium alkyl naphthalene sulfonates, long chain alkyl sodium sulfonates or sulfates, sodium dioctyl sulfosuccinate and so forth. There may also be used neutral non-cationic emulsifying agents such as mannitol monolaurate, the reaction products of protein derivative products with acid chlorides, ethylene oxide reaction products with fatty acids, fatty alcohols and the like.

Emulsions of the copolymers used in accordance with the present invention are preferably but not necessarily those which have been carried to a polymerization. When 100% polymer is obtained, considerable cross linking occurs in the polymer with consequent insolubility in organic solvents. Thus a type of prevulcanizing of the polymer has been obtained. It is also possible to vulcanize the copolymers with mixtures of vulcanizing accelerators such as thiuram disulfide and so forth, vulcanizing agents such as sulfur, dinitrobenzene, alykl phenol sulfide and so forth, either previously or subsequently to deposition or dyeing into the wool fibers.

The treatment of wool fibers is particularly emphasized herein, although animal fibers such as silk and protein fibers such as "Aralac (a casein fiber) may also be treated in accordance with this invention.

After treatment in accordance with the present invention, the wool is rinsed and dried. Its properties have been altered to such a degree that it no longer has a tendency to felt during washing and consequently is non-shrinking. Although it is not intended that the invention be limited by theoretical considerations, it is thought that the copolymer particles applied as set forth in this description distribute themselves among the fibers of the wool and in some instances fill the interstices of the wool scales, thus preventing an intertwining and consequent felting of the wool. Thus the deposited copolymer would prevent intertwining of the wool fibers and also permit relatively easy slippage of the fibers one on the other.

The following examples illustrate the invention, the parts being by weight unless otherwise indicated.

Example 1.-A series of vinyl acetate butadiene copolymer emulsions was prepared with the monomers in the proportions indicated in Table I.

Table I Parts Percent Parts Emulsion No. Vm Pol er Acetate Butadlene Co nt The butadiene was passed over calcium chloride, then condensed and weighed in pressure reactors cooled to below 5 C. The vinyl acetate, which had been previously distilled, was

then added, followed by 100 parts of a bufler solution of pH 11, parts of 30% hydrogen peroxide and 5 parts of sodium lauryl sulfate. The bufi'er solution of pH 11 had been prepared by dissolving 35.8 parts of disodium phosphate and 7.16 parts of trisodium phosphate in 980 parts of distilled water. The reactors were closed, allowed to come to room temperature, and put in an agitator with a constant temperature bath at 45 C.

The reactors were kept in the agitator for 41 hours. At the end of this period they were taken out, cooled and opened. All four reactors showed some pressure and foaming, so that it was necessary to determine the polymer content of each of these emulsions. The results are listed in Table I.

Example 2.The four emulsions made according to Example 1 were applied to hand knit wool samples, approximately 7" x 5" in size.

The weights of the samples are listed in Table 11, together with the amount of emulsion used ior each one. This was the weight of emulsion containing a weight of polymer corresponding to 6% of the weight of the wool sample to be treated. The emulsion was added to 200 parts of water and this bath was conditioned by the addition of 1.0 part of 10% sulfuric acid and 1.0 part of anhydrous sodium sulfate. The wool sample was immersed in the bath at room temperature, and the bath was then heated to 60-70" C. and kept at that temperature. After 20 minutes at 60-'70 C. another portion of 1.0 part of anhydrous sodium sulfate was added. 25-35 minutes after this second salt addition the bath was exhausted, and the wool sample was taken out, rinsed and dried.

These four samples and an untreated control sample were then washed for 6 hours in a washing machine using 25 parts of powdered soap for 13,000 parts of hot water at 70" c. The samples were then rinsed and dried.

Table II amplc Parts gg i'i Shrinkage and Lumber Acetate dime Wool sion Felting 5 45 15. 5e 4. 05 Very considerable. 10 40 14. 65 3. 14 Do. 15 35 16. 81 4. 04 Considerable. 15. 4. 54 Very considerable.

Untreated control sample Very bad.

Table III Parts Parts Emulsion Number Vinyl Chloride Butadwne l 2. 5 22. 6 2 5. 0 20. 0 a 7. 5 l7. 5 4 l0. 0 l5. 0

The butadiene was passed over calcium chloride and condensed in pressure reactors cooled in a Dry Ice-acetone freezing bath. The vinyl chloride was condensed in separate pressure reactors in the same freezing bath as the butadiene. The exact amounts of butadiene and vinyl chloride were then weighed out, and the monomers for the same reaction were then put together in a pressure reactor, one for each of the four emulsions. To each of these reactors, which were still kept in the Dry Ice-acetone bath, were now added parts of a buffer solution of pH 11, 2.5 parts of,10% ammonium persulfate solution and 5.0 parts of sodium lauryl sulfate. The buffer solution of pH 11 consisted of 35.8 parts of disodium phosphate and 7.16 parts of trisodium phosphate dissolved in 980 parts of distilled water. The reactors were then closed, taken out of the freezing bath, allowed to come to room temperature and put in an agitator with a constant temperature bath at 45 C.

After 24 hours in the agitator the reactors were taken out, cooled to room temperature and opened. They showed a slight pressure, but complete polymerization could still be assumed, so that the polymer content of each of these four emulsions was 20%.

Example 4.-The four vinyl chloride butadiene copolymer emulsions made according to Example 3 were applied to 10'" x 10" wool flannel samples, on which four lengths of 8" each had been marked, two lengths in the direction of the warp, two lengths in the direction of the fill.

The wool samples weighed 12.5-13.0 parts. An amount of emulsion containing a weight of polymer corresponding to 4.5% of the weight of the wool sample to be treated was added to approximately 260 parts of water (20 times the weight of the wool sample) and 2.0 parts of 50% acetic acid. Approximately 3.5 parts of anhydrous sodium sulfate (26.5% of the weight of the wool sample) were dissolved in 50 parts of water.

The wool sample was wetted in water at 30 C. for 10 minutes and immersed in the bath at room temperature containing the emulsion and the acid. The bath was then heated to 60 C. in the course of 15 minutes. Half of the salt solution was added. After 15 minutes at 60 C. the second half of the salt solution was added and the bath kept at 60 C. until exhaustion occurred 3545 minutes after the second salt addition. The sample was then rinsed, dried and measured.

Table IV St -'5 rm 'age Sample Number gfi ggz 35 Felting Warp rm 1 2. 5 22. 5 8. 2 2. 7 Slight. 2 5. O 20. O 7. l 5. 3 D0. 3 7. 5 l7. 5 7. 7 2. 8 D0. 4- l0. 0 15. 0 8. 3 2. 8 D0. 5... Control Sample 28. 4 13.2 Bad.

These four samples and one untreated control sample were washed for 6 hours in a washing machine using 35 parts of powdered soap for 18,500 parts of hot water at 70 C. The samples were then rinsed, dried and measured.

Table IV shows the extent of the shrinkage and felting caused by the washing and these data indicate that all four emulsions are very good shrinkproofing and feltproofing agents.

Having thus set forth my invention, I claim:

1. A bath suitable for shrinkproofing wool while retaining essentially normal hand which comprises an aqueous substantially stable emulsion containing a synthetic copolymer of 100% polynerization of butadiene-1,3 and from 10 to 50% by weight on that copolymer of a vinyl ester selected from the group consisting. of halides and fatty acids, the latter having not more than 6 carbon atoms, in amount to give 1 to 25% by weight of copolymer deposition on the wool, a non-cationic emulsifying agent,-and at least 25% by weight on the copolymer of a water-soluble neutral salt of an alkali metal as conditioning electrolyte, the pH of the bath being below 7.

2. A bath as set forth in claim 1, in which the emulsifying agent is anionic.

3. A bath as set forth in claim 1, in which the vinyl ester is vinyl chloride.

4. The method of shrinkproofing wool which comprises immersing the wool in a heated bath as set forth in claim 1 at a temperature of from 40 C. to the boiling point of the bath.

5. A bath as set forth in claim 1, in which the vinyl ester is vinyl acetate.

6. A bath as set forth in claim 1, in which the vinyl ester is a vinyl ester of a fatty acid of not more than 6 carbon atoms.

JOHN B. RUST.

REFERENCES CITED The following references are of record in the file of this patent:

10 Number UNITED STATES PATENTS OTHER REFERENCES Barron Modem Synthetic Rubber (2nd ed., no 1944), pales 1521-166. 

1. A BATH SUITABLE FOR SHRINKPROOFING WOOL WHILE RETAINING ESSENTIALLY NORMAL HAND WHICH COMPRISES AN AQUEOUS SUBSTANTIALLY STABLE EMULSION CONTAINING A SYNTHETIC COPOLYMER OF 100% POLYMERIZATION OF BUTADIENE-1,3 AND FROM 10 TO 40% BY WEIGHT ON THAT COPOLYMER OF A VINYL ESTER SELECTED FROM THE GROUP CONSISTING OF HALIDES AND FATTY ACIDS, THE LATTER HAVING NOT MORE THAN 6 CARBON ATOMS, IN AMOUNT TO GIVE 1 TO 25% BY WEIGHT OF COPOLYMER DEPOSITION ON THE WOOL, A NON-CATIONIC EMULSIFYING AGENT, AND AT LEAST 25% BY WEIGHT ON THE COPOLYMER OF A WATER-SOLUBLE NEUTRAL SALT OF AN ALKALI METAL AS CONDITIONING ELECTROLYTE, THE PH OF THE BATH BEING BELOW
 7. 